The stock carbs are okay, but like most of these weedie carbs, the venturi are relatively small. If you're looking to increase HP, you may want to go to a larger carb.

The last rotating barrel carb I saw was a fixed jet Walbro(?) - pretty much useless for RC. It's sitting in a bin with of other carbs waiting to be traded in at the local lawn equip. shop for other goodies.